remove a bunch of locking from LLVMContextImpl. Since only one thread

can be banging on a context at a time, this isn't needed.  Owen, please
review.

llvm-svn: 85728

1 files changed, 3 insertions, 0 deletions

diff --git a/llvm/lib/Transforms/Scalar/SimplifyCFGPass.cpp b/llvm/lib/Transforms/Scalar/SimplifyCFGPass.cpp
index 29712b3c13d..6a8148040d9 100644
--- a/llvm/lib/Transforms/Scalar/SimplifyCFGPass.cpp
+++ b/llvm/lib/Transforms/Scalar/SimplifyCFGPass.cpp
@@ -126,6 +126,9 @@ static bool MarkAliveBlocks(BasicBlock *BB,
         }
       }
       
+      // Store to undef and store to null are undefined and used to signal that
+      // they should be changed to unreachable by passes that can't modify the
+      // CFG.
       if (StoreInst *SI = dyn_cast<StoreInst>(BBI)) {
         Value *Ptr = SI->getOperand(1);